Bloodstain pattern analysis is one of the most challenging areas of forensic science. Often criticized as subjective and uncertain, it nonetheless remains a valuable tool in helping investigators draw conclusions about what happened at the scene of a violent crime—especially as technology advances make it more reliable.
In the past, analysts relied primarily on a combination of stringing and hand mathematical calculations using the Balthazard formula and the tangent method. This approach is time-consuming, involves multiple people, and introduces the risk of measurement uncertainty and calculation errors.
More recently, 3D laser scanning has become widely accepted as the most accurate and effective way to capture and analyze bloodstain patterns. The laser scanner quickly captures comprehensive data of the entire scene, including blood spatter, and freezes it in time with millions of accurate data points and 360 imagery for analysis and visualization. But there is still the matter of combining the data with the other evidence.
“Bloodstain pattern analysts have a variety of backgrounds; some are investigators, some are crime scene investigators and reconstructionists, and some are bench scientists,” says Crime Scene Investigator Amy Santoro, MFS, CSCSA, with the Johnson County Sheriff’s Office Criminalistics Laboratory in Olathe, KS. “It’s so important that we’re integrating all the information from the scene together for juries and investigators to give all interested parties a clear picture of what the evidence means.”
Software Integration Saves Time, Reduces Error
Achieving this integration hasn’t always been easy. While software exists that can perform calculations and analyze bloodstain patterns captured with 3D laser scanning, workflows are often cumbersome. Importing and exporting the data and creating reports can require multiple steps.
Newer approaches streamline the process by allowing you to integrate scan data with high-resolution photographs and create area-of-origin calculations in a 3D dataset directly within your scene mapping software, such as Map360, as part of a BPA-validated workflow. “With Map360 and the BPA workflow, we can integrate our scan data, our bloodstain data analysis, crime scene images, even crime laboratory reports into one deliverable,” says Santoro. “Having the ability to integrate area of origin calculations into a three-dimensional rendering of the scene is a benefit that can’t be ignored, and the output is amazing.”
>>RELATED: Go behind the scenes on the Map360 Bloodstain Pattern Analysis tool in a on-demand Lunch & Learn webinar.
Map360 allows you to identify lead stains to include in the analysis (above) as well as analyze impact patterns, define the area of origin, and produce a 2D or 3D visualization of the crime scene.
“There’s so much more though,” she adds. “The workflow allows users to save time on scene because photography is so much easier and hand measurements can be eliminated. By reducing what the analyst has to do, we’re not only saving time, we’re also reducing opportunities for error.”
Technology Strengthens the Science of Bloodstain Pattern Analysis
As visualization becomes increasingly important during investigations and in the courtroom, strings and hand measurements are no longer adequate. “Ultimately, what we find as investigators and scientists needs to be communicated to trier of fact, usually in a courtroom,” Santoro says. “What seems intuitive to an experienced bloodstain pattern analyst can be challenging for a layperson to understand, so having a visual representation for a juror to look at can be so helpful.”
Taking that visualization into 3D space with laser scanning and point cloud data gives jurors the ability to understand even more. “We’ve all heard the old adage, the benefit of a photograph is the ability to look again,” she says. “With point cloud data we have not only the ability to look again, but the ability to look, measure and analyze again—and that’s pretty much invaluable.”
Moving from criticism to acceptance, however, requires advancing to the next level and using software that integrates the point cloud data with other scene evidence. “Tools like Map360 with the BPA workflow are the future of our discipline,” Santoro says. “Attorneys and jurors alike are so used to seeing high-tech options in the courtroom, and the BPA workflow really helps modernize this area of BPA. It’s no secret that our discipline has received some criticism from people who believe it’s more of an art than a science. Using a tool like the Map360 workflow really helps to demonstrate that area-of-origin determinations are based on strong science and mathematical principles.”
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